Performance Requirements (ASCE)

According to ASCE 41-23 section 2.4, the objectives of the assessment or redesign (Table C2-8) consist of combinations of both a performance level and a seismic action, given an "acceptable probability of exceedance within the life cycle of the building" (design earthquake), as shown in Table C2-8 of ASCE 41-23 below:

The target building performance levels refer to the state of damage in the structure defined through four limit states, namely Operational Level (1-A), Immediate Occupancy (1-B), Life Safety (3-C) and Collapse Prevention (5-D).

Performance Level of Operational Level (1-A)
The Operational Level (1-A), according to ASCE 41-23, is a condition in which it is expected that damage is insignificant and structure does not need any repair measures. Structural elements are prevented from significant yielding and retaining their strength and stiffness properties. All systems important to normal operation are functional. Non-structural components, such as partitions and infills should not be damaged.

Performance Level of Immediate Occupancy (1-B)
The Immediate Occupancy after the earthquake (1-B), according to ASCE 41-23, is a condition in which it is expected that no building operation is interrupted during and after the design earthquake, with the possible exception of minor importance functions. Structural elements are retaining their strength and stiffness properties. A few hairline cracks may occur in the structure

Performance Level of Life Safety (3-C)
The Life Safety (3-C), according to ASCE 41-23, is a condition in which moderate damage to the structure is expected to occur during the design earthquake, although it is likely to be uneconomic to repair. Structural elements are retaining some residual strength and stiffness. Non-structural components are damaged, although partitions and infills have not failed out-of-plane. Moderate permanent drifts are present.

Performance Level of Collapse Prevention (5-D)
The Collapse Prevention (5-D), according to ASCE 41-23, is a condition in which severe (non-repairable, in general) damage to the structure is expected during the design earthquake and would probably not survive another earthquake. The structure is heavily damaged with low residual lateral strength and stiffness, although vertical elements are still capable of sustaining vertical loads. Most non-structural components have collapsed and large permanent drifts are present.

The criteria for the selection of the Performance Objectives may be found in ASCE 41-23.